煤层底板隐伏陷落柱突水预测及采前注浆加固评价

华北型煤矿开采受底板岩溶强含水层威胁,通过对淮南张集矿1613A工作面底板隐伏岩溶陷落柱突水危险性分析,采用FLAC3D方法模拟采动条件下岩溶陷落柱活化过程。模拟结果显示:陷落柱上方的煤层底板岩体发生塑性变形,导致陷落柱附近岩体失稳,陷落柱筒壁产生局部剪切破坏,剪切破坏位置易导致奥灰强含水层发生陷落柱突水。采前采用注浆方法改造岩溶陷落柱,对改造后的陷落柱进行数值模拟分析,其内部注浆岩体对陷落柱筒壁具有良好的支撑作用,抑制了筒壁位置剪切破坏的发生,使有效隔水层厚度增大,降低了陷落柱突水的危险性。

Prediction of water inrush from hidden collapse column at coal seam floor and evaluation of grouting reinforcement before mining

The coal mining of North China Type coalfields has been threatened by the karst strong aquifer at floor. The hazard of water inrush from the hidden karst collapse column at the floor of 1613A working face in Zhangji Mine, Huainan was analyzed, and the activation process of karst collapse column under the mining conditions was simulated by using the FLAC3D method. The simulation results showed that the rock mass at the coal seam floor above the collapse column occurred the plastic deformation, which caused the instability of rock mass near the collapse column, and the barrel wall of collapse column occurred the local shear failure, so the water inrush from collapse column in the ordovician limestone strong aquifer was easily to occur in the position of shear failure. The karst collapse column was transformed by using the grouting method before mining, and the numerical simulation analysis was conducted on the collapse column after transformation. The rock mass with internal grouting played good support role on the barrel wall of collapse column, which prohibited the occurrence of shear failure in the position of barrel wall, increased the thickness of effective aquifuge, and reduced the hazard of water inrush from collapse column.